Yesterday, “The Killing” star Mireille Enos announced she was expecting her second child with husband . . . Alan Ruck? The “Ferris Bueller” guy? Who else didn’t we know was an item? Here’s a handy guide to TV-star couples, some of whom also appear as onscreen love interests.

Mireille Enos and Alan Ruck

Photo: Jesse Grant/WireImage

Enos, the 38-year-old star of “The Killing,” and Ruck, her 57-year-old husband and “Spin City” star, told People in a statement: “We are so excited and feel so unbelievably lucky to have this little person coming to us!” The couple married in 2008.

Nina Dobrev and Ian Somerhalder

Photo: Mark Davis/Getty Images for The People's Choice Awards

The “Vampire Diaries” co-stars dated for three years, then broke up last August, but are rumored to have gotten back together. Dobrev, 25, and Somerhalder, 35, recently saw their characters finally get together on the show, too.

Kat Dennings and Nick Zano

Photo: David Tonnessen/PacificCoastNews.com

Dennings, 27, is the star of “Two Broke Girls,” where she met Zano, 35, who plays her character’s occasional love interest. Despite rumors they had broken up and that she was dating Drake, Dennings recently Instagrammed a cozy photo of her and Zano together.

Emily VanCamp and Josh Bowman

Photo: Splash News

The “Revenge” stars have been dating for two years; Bowman, 25, plays the fiancé of VanCamp, 27, on the ABC show. The two were recently spotted holding hands while out to lunch in Los Feliz, Calif.

Sarah Shahi and Steve Howey

Photo: Sara Jaye Weiss/StartraksPhoto.com

Shahi, 34, stars on “Person of Interest,” while Howey, 36, is on “Shameless.” The two married in 2009 and have one son; they recently vacationed with friend Max Greenfield (“New Girl”) and his wife and daughter.

Chris Pratt and Anna Faris

Photo: Splash News

“Parks and Recreation” star Pratt, 34, married Faris, the 37-year-old recent star of “Mom,” in 2009; the two have one son, but Pratt recently told Ellen DeGeneres he wants to have another ASAP.

Peter Krause and Lauren Graham

Photo: Jason LaVeris/FilmMagic

Krause, 48, and Graham, 46, play siblings on the NBC show “Parenthood,” but they’ve been an offscreen item since 2010. Krause has said they kept it on the down-low for nearly a year before telling their co-stars.

Taran Killam and Cobie Smulders

Photo: Jim Spellman/WireImage

“SNL” star Killam, 31, and the “How I Met Your Mother” star, also 31, got engaged and had a child in 2009; they didn’t tie the knot until 2012. Killam recently told Vulture, “Every day with Cobie is a honeymoon!”

John Slattery and Talia Balsam

Photo: George Pimentel/Getty Images for Sundance Film Festival

On “Mad Men,” Slattery’s character, Roger Sterling, was none too kind to his now-ex-wife, Mona; but in real life, they’ve been happily married since 1998 and have a son. “It’s great acting with my wife. We don’t have to invent any history or backstory because it’s all there and it just makes the job a lot easier,” Slattery, 51, told the Daily Mail about his wife, 54.

Vincent Kartheiser and Alexis Bledel

Photo: Clint Spaulding/PatrickMcMullan.com

On “Mad Men,” Bledel, the 32-year-old former “Gilmore Girls” star, had a guest-story arc in which she played a married woman who had an affair with Pete Campbell, portrayed by Kartheiser, 34. In real life, the couple got together on set in 2012 and announced their engagement in 2013.